1. Field of Application
The present invention relates to a semiconductor component with trench isolation and to an associated fabrication method, and, in particular, to a semiconductor component with a trench-type, bottom-contact-connected active shielding and to an associated fabrication method.
2. Background Information
Isolations for defining, in particular, active regions in semiconductor substrates have usually been formed by thick oxide films, so-called local oxidation regions (LOCOS, Local Oxidation of Silicon). As the integration density rises, however, such conventional LOCOS methods are no longer suitable since they have a high area requirement. What is more, they exhibit the so-called “birds beak” phenomenon, with insulation layers forming laterally in the direction of the active regions. Therefore, so-called trench isolations have been developed, in which case, for example in accordance with shallow trench isolation (STI), a shallow isolation trench filled with insulating material is formed at the surface of a semiconductor substrate. Nevertheless, such a conventional trench isolation is also often insufficient since so-called punch-through effects occur in the semiconductor material. Undesirable leakage currents are observed in this case. In the extreme case, parasitic bipolar transistors may be triggered by these leakage currents and semiconductor components may therefore be destroyed.
Trench isolations with a shielding structure have recently been developed in particular for the purpose of reducing such leakage currents, in which case, in order to realize a field shielding in the trench, an electrically conductive material is embedded as electrode and leads to improved electrical properties. Such trench isolations with shielding action are usually contact-connected at the substrate surface or from the substrate.
What are disadvantageous in this case, however, are an inadequate shielding action and/or an increased area requirement on account of the necessary contact connection.